The intake manifold routes fuel/air compound to the cylinder heads.
Besides, the tunnels are of at odds lengths in that the carburettor sits in the Centre of the engine and the cylinders' locations gamut from directly below the carburettor to the far confine of the engine. The tunnels must be designed so that air flow arrives at the cylinder intellect at the genuine continuance.
Resonance
Air continues travelling down the tunnels, or runners, after the intake valve closes. It bounces off the closed valve and rushes back up the runner until it hits the carburettor or fuel injector and bounces off back toward the closed valve. It travels at the speed of sound, 330 meters per second at sea level, and will make several trips back and forth before the valve opens again. The air inside the runner forms a sound wave with areas of high density and low density. The designers of the intake manifold tune the runner as if it were a pipe in an organ by making it longer or shorter. They want to create a situation in which an area of high density hits the valve just as it opens, forcing more fuel/air mixture into the combustion chamber.The engine runs at different speeds, which make the sound waves travel at different speeds. This, and the difference in length of the runners, makes it impossible to tune the runners perfectly.The intake manifold connects the carburettor with the cylinder purpose and, ended the cylinder belief, the combustion chambers. It delivers the fuel/air concoction buttoned up gangling tunnels. The shape and dimensions of the tunnels and the ports that connect it to the the carburettor and the cylinder purpose involve the efficiency of the engine.
Intake Manifold Complexities
The tunnels inside the intake manifold gain to fabricate turns to receive from the carburettor or fuel injectors to the cylinder belief. Provided the designers of the manifold constitute the turns also sharp or levy in very many of them, the fuel/air compound won't be delivered to the cylinder belief at the exactly quickness.The designers aim for a compromise in which the runners deliver the highest density to the most combustion chambers over the highest percentage of the range of engine speed.
Size, Horsepower and Money Matter
The size of the ports, or inlets, and the size of the runners makes a major difference in the performance of the engine. They must be big enough to deliver the fuel/air mixture required by the engine for peak performance but no bigger. Intake manifolds require metal and machining and can be very costly to make.
Drivers who want more horses under the hood can replace the intake manifold for very little money and get good results. The mechanics at "Car Craft" magazine swapped the stock carburetor and intake manifold on a 1967 Camaro and gained 30 horsepower. It cost less than $500 in 2009.
